test(Avatar): cover CSS size override regression

[liuliu-dev]

Related to #8550

Adds development-only Avatar browser coverage for consumer CSS size overrides. The test asserts the computed width and height before taking VRT screenshots, catching the stretching regression observed when testing #8550 against github-ui.

Changelog

New

• Avatar regression coverage for CSS size overrides.

Changed

• None.

Removed

• None.

Rollout strategy

• No changes needed in github/github-ui
• Needs changes in github/github-ui
• Ships with feature flag(s)
• Not sure
• None — Test-only coverage; no rollout is required.

Testing & Reviewing

• npm run build — passed
• STORYBOOK_URL=http://localhost:6006 npx playwright test e2e/components/Avatar.test.ts --grep 'CSS Size Override Regression' --update-snapshots — 9 passed
• With Fix/avatar button leading visual sizing #8550 temporarily applied, the same targeted test produced 9 expected failures: width expected 16px, received 20px.

[changeset-bot]

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Latest commit: e2aebcf

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[Copilot]

🟡 Changes recommended

Nine required screenshot baselines are missing, causing normal visual regression runs to fail.

1 open finding

• Add missing Linux baselines for nine Avatar screenshot tests · New

What changed in this PR

Adds development-only Avatar regression coverage for consumer CSS size overrides, targeting the stretching observed with #8550. No runtime behavior changes.

Changes:

• Adds an Avatar fixture with 16px CSS width and height.
• Checks computed dimensions before screenshots across nine themes.

File	Description
packages/​react/​src/​Avatar/​Avatar.dev.stories.tsx	Adds the CSS size override fixture.
e2e/​components/​Avatar.test.ts	Adds dimension assertions and themed screenshot coverage.

🧠 Review effort: Balanced

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